HOV (high occupancy vehicle) lanes have been in the news over the last few years, and will be so more and more often. They are the preferred option by Caltrans and other transportation agencies (which often have to fund these largely on their own dime) for increasing highway capacity. Notice that I said increasing capacity rather than reducing congestion. Caltrans claims that they reduce congestion (see Caltrans HOV page), but there is no evidence to support that, and much to controvert it. Though Caltrans officially acknowledges the concept of induced demand, it is not used in their highway planning. The mid-level engineers in Caltrans, who largely determine the actual projects selected and the design of those projects, don’t believe in induced demand. They say so regularly. But induced demand is a proven effect, and any project planned without that in mind is going to be mis-designed.
Communities have grown increasingly resistant to the expansion of freeways, which largely or entirely benefit long distance commuters and provide almost no benefit, and often strong negatives, to the neighborhood, and little benefit to productive freight traffic. The era of the freeway is over, and many exiting freeways will be torn down eventually, but Caltrans is still on a building jag. Knowing the resistance, however, Caltrans rarely proposes new general purpose lanes (lanes which any one can drive in, without restriction), instead proposing HOV lanes. Somehow, these seem to get a pass from communities and environmentalists, figuring that a HOV lane expansion is better than a general purpose lane expansion. Well, yes, but the question is, should there be any expansion at all?
If some high capacity vehicles are diverted out of general purpose lanes, that provides a more open lane, and that more open lane will be filled with additional traffic. The HOV lane itself, being more open than adjacent lanes, will create additional traffic. Drivers respond to their perception of crowding and delay. If they see more space, they will drive more. Induced demand, simple as that. So a HOV lane increases overall traffic. Cost is an issue, as most of our transportation dollars at the state and regional level go to these projects, instead of projects that would actually reduce private vehicle use and vehicle miles traveled. Environmental and social impacts increase. And the lanes fill up, creating a demand for yet more lanes in a never-ending cycle.
A $133M project called 80 Across the Top has been completed, which added HOV lanes to Interstate 80 from the river to Watt Ave. Note that cost does not include loss of productivity during construction, which if the news media is to be believed, was considerable, nor the elevated crash rate during the project. Now Caltrans is well underway with a $187M project to add HOV lanes to Hwy 50, and is out selling the idea of adding HOV lanes to Business 80 (Capital City Freeway). Meanwhile, a number of people have proposed tearing down the Capital City Freeway, including this blog. The river bridge would not be torn down, but the transportation facility north and south of the bridge would be a surface roadway rather than elevated freeway, and capacity on the bridge could be made available for other modes. Or maybe the bridge should be torn down and replaced with an appropriately scaled neighborhood bridge (similar to what is being talked about for the Broadway extension bridge over the Sacramento River).
Next up: the solution for HOV